1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, a printer, or other similar image forming apparatus, and more particularly to an image forming apparatus including a heat shielding device that shields an image forming device from heat radiated from a heat fixing device.
2. Discussion of the Background
An electrophotographic image forming apparatus generally includes an image forming device having a photoreceptor, a charging device, a developing device, a transfer device, a cleaning device to perform an electrophotographic process; a heat fixing device that fixes a toner image on a transfer sheet; an image reading optical system that reads an image of an original document; an image writing optical system that writes image information onto the photoreceptor; and a sheet feeding device that feeds a transfer sheet to the image forming device.
The heat fixing device includes a heat roller having a heater inside thereof and a pressure roller press-contacted onto the heat roller. A toner image, which is transferred onto a transfer sheet in the image forming device, is fixed onto the transfer sheet by heat and pressure in the heat fixing device.
Due to an increasing demand for downsizing an image forming apparatus, devices in the image forming apparatus tend to be provided close to each other. Accordingly, an image forming device and a heat fixing device tend to be located adjacent to each other. In this case, elements in the image forming device may tend to be badly influenced by heat radiated from the heat fixing device. For example, in a developing device that contains toner, the toner in the developing device is likely to cohere due to the heat generated in the heat fixing device. In a cleaning device, if the toner collected by the cleaning device coheres due to the heat generated in the heat fixing device, the collected toner may not be conveyed smoothly.
In order to prevent an image forming device from heat radiated from a heat fixing device, for example, Japanese Laid-open Patent Publication No. 11-344916 describes an image forming apparatus including a heat shielding device in which an amount of heat transmitted from a heat fixing device to an image forming device is reduced by use of a heat shielding plate provided with heat pipes. As compared to a heat shielding device using an air duct or a heat sink, the size of the apparatus may be reduced by using the heat shielding plate and heat pipes.
An image forming apparatus including a heat shielding device that can efficiently shield an image forming device from heat radiated from a heat fixing device while saving space has been desired.